Gas discharge devices commonly employ a pair of electrodes for passing an electrical current through the gas within a gas containing cavity and subsequently initiating a gas discharge. Such gas discharge devices are commonly employed in lasers. However, in laser applications, the electrical current passing through the gas is commonly controlled so as to establish appropriate characteristics of the laser beam. This is particularly important in ring laser gyros as those shown and described in U.S. Pat. No. 3,373,650, issued to Killpatrick, and U.S. Pat. No. 3,390,606, issued to Podgorski.
In the aforesaid ring laser gyro, commonly employed is a single cathode and a pair of anodes in which the total electrical current between each pair of electrodes must be held constant to within a fraction of a percent to prevent changes in what is referred to as the ring laser gyro output bias. Further, not only are the electrical currents between the cathode and each of the anodes maintained substantially equal, but the total current passing into and out of the cathode is held constant within a fraction of a percent to prevent changes also in the gyro output bias.
To achieve this goal in ring laser gyros, designers generally build high voltage supplies to overcome the large resistance of the gas discharge cavity, and then the electrical currents flowing into and out of the cathode is carefully measured using sensitive, precision components, and compared to a stable reference current or voltage. This comparison is then used to create an error signal which is then fed back to a high voltage current control circuit which is electrically connected to a high voltage electric potential source.
In operation, such circuits function so that if the current begins to deviate slightly from a desired amount, the error signal that is generated is sent back to the current control circuit to compensate, thereby forcing the current to be regulated.
In such systems it is important to translate the low voltage error signal provided from a low voltage measuring circuit to the high voltage current control circuit. Simple wire connections would allow dangerous high voltages to flow back to the low voltage measuring circuits and may subsequently damage them by exceeding their respective voltage ratings. In the prior art, a common solution has been to use several stages of transistors to isolate the high voltage circuitry from the low voltage measuring circuits.